1. Field of the Invention
The present invention relates to a process cartridge and an electrophotographic image forming apparatus to which the process cartridge is detachably mountable.
Here, the electrophotographic image forming apparatus may be, for example, an electrophotographic copying machine, an electrophotographic printer (for example, LED printer, laser beam printer or the like), an electrophotographic facsimile, an electrophotographic word processor, or the like.
Further, the process cartridge may incorporate therein an electrophotographic photosensitive member and at least one of charging means, developing means and cleaning means as a cartridge unit which can be detachably mounted to a main body of the image forming apparatus or may incorporate therein an electrophotographic photosensitive member and at least developing means as a cartridge unit which can be detachably mounted to a main body of the image forming apparatus.
2. Related Background Art
In conventional electrophotographic image forming apparatuses using an electrophotographic image forming process, a process cartridge in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally incorporated as a cartridge unit which can be detachably mounted to a main body of the image forming apparatus has been utilized. According to the process cartridge system, since maintenance of the apparatus can be performed by the user without any expert, operability can be improved considerably. Thus, the process cartridge system has widely been used in the electrophotographic image forming apparatus.
Among such electrophotographic image forming apparatuses of the process cartridge type, there is an image forming apparatus including means for informing the user of the fact that developer is depleted, i.e., a developer amount detecting device.
As the developer amount detecting device, a device in which two electrode rods are disposed within a developer container of developing means and a developer amount is detected by detecting a change in capacitance between the two electrode rods is known.
Further, Japanese Patent Application Laid-Open No. 5-100571 discloses a developer amount detecting device comprising, in place of two electrode rods, a developer detecting electrode member obtained by combining two parallel electrodes interdigitated with each other on the same plane with a predetermined distance therebetween and in which the developer detecting electrode member is located on a lower surface of a developer container. This device serves to detect a developer remaining amount by detecting a change in capacitance between the parallel electrodes in a flat plane.
However, both of the above-mentioned developer amount detecting devices detect the presence and absence of the developer in the developer container, i.e., detect that the amount of the developer is small immediately before the developer in the developer container is depleted, but do not detect how much developer remains in the developer container.
On the other hand, if the developer remaining amount in the developer container can be detected stepwise, the user can know or recognize the developer using state in the developer container, with the result that a new process cartridge can be prepared in accordance with the exchanging time. This is very convenient for the user.
An object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus, in which a developer remaining amount can be detected successively.
Another object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus, in which a developer remaining amount can be detected stepwise in accordance with the consumption of the developer in a developer container constituting a developer containing portion.
A further object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus, which includes a developer amount detecting device having less detection error by eliminating the measurement error caused by a change in environment when a developer remaining amount is detected by detecting a change in capacitance between electrodes and in which user""s convenience in usage of the apparatus is improved.
A still further object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus, in which distances between juxtaposed portions of input and output electrodes of a plurality of measuring electrode members are different from a measuring electrode member to a measuring electrode member.
These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.